hhr293 commented on code in PR #12756: URL: https://github.com/apache/gluten/pull/12756#discussion_r3931190189
########## backends-velox/src/main/scala/org/apache/gluten/extension/RewriteSelfJoinInequalityToAggregate.scala: ########## @@ -0,0 +1,734 @@ +/* + * Licensed to the Apache Software Foundation (ASF) under one or more + * contributor license agreements. See the NOTICE file distributed with + * this work for additional information regarding copyright ownership. + * The ASF licenses this file to You under the Apache License, Version 2.0 + * (the "License"); you may not use this file except in compliance with + * the License. You may obtain a copy of the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, software + * distributed under the License is distributed on an "AS IS" BASIS, + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + * See the License for the specific language governing permissions and + * limitations under the License. + */ +package org.apache.gluten.extension + +import org.apache.gluten.config.VeloxConfig + +import org.apache.spark.internal.Logging +import org.apache.spark.sql.SparkSession +import org.apache.spark.sql.catalyst.expressions._ +import org.apache.spark.sql.catalyst.expressions.aggregate._ +import org.apache.spark.sql.catalyst.plans._ +import org.apache.spark.sql.catalyst.plans.logical._ +import org.apache.spark.sql.catalyst.rules.Rule +import org.apache.spark.sql.execution.datasources.{HadoopFsRelation, LogicalRelation} +import org.apache.spark.sql.execution.datasources.parquet.ParquetFileFormat +import org.apache.spark.sql.types.{BinaryType, BooleanType, ByteType, DataType, DateType, DecimalType, IntegerType, LongType, ShortType, TimestampType} + +/** + * Rewrites self-join with inequality into GROUP BY + HAVING COUNT(DISTINCT) > 1. + * + * Targets the two uncorrelated InSubquery shapes exercised by TPC-DS Q95: + * + * - Pattern A': the subquery top-level InnerJoin is a direct self-join. + * - Pattern A2: the subquery contains an outer InnerJoin with a self-join child; only the + * self-join child is replaced with Aggregate and the outer join is preserved. + * + * Both patterns require an existence-only membership context so row-count multiplicity from the + * original self-join cross-product does not affect semantics. Correlated InSubquery expressions are + * intentionally fail-closed because the ExprId remapping performed here does not rewrite correlated + * predicates. + * + * Both patterns share: + * - [[buildAggregateHavingDistinctGt1]] to construct `Filter(cnt > 1, Aggregate)` + * - [[canonicalizeWrapper]] to rebuild a wrapping Project so every equi-key reference points to + * the sjLeft-side attribute, with **fresh exprIds** (Spark's SPARK-21835 style -- no reuse of + * original exprIds), returning an old->new attribute remap for downstream rewrite. + * + * Controlled by `spark.gluten.sql.rewrite.selfJoinInequality` (default false, opt-in). + */ +case class RewriteSelfJoinInequalityToAggregate(spark: SparkSession) + extends Rule[LogicalPlan] + with PredicateHelper + with Logging { + + private val CountDistinctAliasName = "_gluten_rw_selfjoin_cnt_distinct" + + override def apply(plan: LogicalPlan): LogicalPlan = { + if (!VeloxConfig.get.enableRewriteSelfJoinInequality) { + logDebug("RewriteSelfJoinInequalityToAggregate: disabled via config, skipping") + return plan + } + + // Pattern A' / A2: rewrite uncorrelated InSubquery plans. + // Correlated subqueries carry outer references / correlated join conditions in + // `SubqueryExpression.children`; fail closed because this rule does not remap them. + val rewritten = plan.transformAllExpressions { + case in @ InSubquery(_, lq: ListQuery) if lq.children.isEmpty => + rewriteSubqueryPlan(lq.plan) match { + case Some(newSub) => in.copy(query = lq.copy(plan = newSub)) + case None => in + } + } + if (!(rewritten eq plan)) { + logDebug( + "RewriteSelfJoinInequalityToAggregate: rewrote self-join to " + + "GROUP BY + HAVING COUNT(DISTINCT) > 1") + } + rewritten + } + // ============================================================================ + // Shared helpers + // ============================================================================ + + /** + * Build `Filter(cnt > 1, Aggregate(equiKeys, [equiKeys, cnt_alias], Filter(IsNotNull(equiKeys), + * child)))`. Returns the Filter node whose output is `equiKeys ++ [count_alias_attr]`. + * + * The extra `IsNotNull(equiKeys)` filter is essential to preserve the original equi-join's NULL + * semantics. Under SQL 3VL, `left.k = right.k` never matches when either side is NULL, so the + * original self-join drops rows with NULL equi-keys. Aggregate, in contrast, groups NULL keys + * together into a single "NULL group" -- if that group has >= 2 distinct non-null neq values, + * COUNT(DISTINCT) > 1 fires and injects NULL into the subquery output. That leaked NULL then + * turns `NOT IN` into a spurious empty result (Spark's null-aware anti-join uses + * `Or(equi, IsNull(equi))` which any NULL sub-row satisfies) and can flip IN/NOT IN outcomes. The + * neq column needs no such filter: `COUNT(DISTINCT col)` already ignores NULL. + */ + private def buildAggregateHavingDistinctGt1( + equiKeys: Seq[Attribute], + neqCol: Attribute, + child: LogicalPlan): LogicalPlan = { + val countExpr = AggregateExpression( + Count(Seq(neqCol)), + mode = Complete, + isDistinct = true, + filter = None, + NamedExpression.newExprId) + val countAlias = Alias(countExpr, CountDistinctAliasName)() + // Seq[Attribute] is a Seq[NamedExpression] via covariance; no cast needed. + val aggExprs: Seq[NamedExpression] = equiKeys :+ countAlias + val nonNullChild = equiKeys Review Comment: Agreed. I’ll narrow the NULL comment to NOT IN semantics; the implementation stays unchanged. -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. 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